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Fouled iridium spark plugs cause?

wod300

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I bought a VX super6 Berlina about 4 months ago from a guy who had owned it since new with log book history. Until recently the car has run perfectly. So far I've done:

10psileads, by mace
Cold air intake by mace
Cat back exhaust
Memcal from mace
Shift kit

For the last few weeks I've noticed that the car has started hesitating/missing under acceleration. I had the filterschanged today, and the plugs and leads, which has fixed the problem. But now I'm a bit worried because, while the oil was still in good condition, the iridium plugs that were in their don't look too good. According to The previous owner, the plugs are around 30,000kms old. I've taken some pictures of the plugs I took out and one of them looks pretty bad (the mechanic didn't tell me which cylinder each one came from).

Could anyone tell me what might be wrong by looking at the pictures? I'm hoping its nothing too bad. Thanks.

plugs.jpgplugs3.jpg

This is the one with carbon (?) deposits
plugs2.jpg

plugs4.jpgplugs5.jpg
 

Super_Low 91

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I use this chart when looking at plugs to see how they are. It looks like yours are a combination of a couple of them kinda hard to tell.
 

wod300

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Thanks for that.
One thing I noticed was that the gap seemed to be far too wide. They were over 2mil so I don't know if that could be the cause.

Maybe I need to look at colder plugs?

Sent from my GT-I9505 using Tapatalk 4
 

Tree cutter

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The gaps look far too wide to me too. The plug that is fouled has been getting oil on it. It could be anything causing oil to get in to that cylinder. You need to take your new plugs out and check to see which one has oil cooked onto it again and then start looking to find what the cause is. It could be leaking valve stem seals or worn valve guides. Broken rings or a cracked piston could be another cause, or it might just be the PCV valve letting oil in.
 

Tasmaniak

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gap on platinums and iridiums are preset and theoretically should not be changed.
 

Jxfwsf

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Looks like 1 cylinder in particular is really bad, if they're from the same bank (assuming they're pulled out and lined up for the pics.... but hard to tell if the mechanic didn't take note) the 2nd one showing a darker color could be a sign of something in that bank, although with the marks so far up the thread it may just not have been seated correctly and it's just unburnt combustion gasses in that one messing up everything.
Doesn't seem the electrodes are burnt out at all so to me this rules some problems out, looks more like oil/over fueling contamination built up instead.

Imo 4 of the 6 look fine, You haven't mentioned how many km's overall the engine has done, could be an inlet manifold gasket, lazy o2 sensor..... It's not using coolant or oil?

Best test i would suggest would be to have a tech2 hooked up, run the power balance and see if all cylinder are even... alternatively the back yard method, with it idling undo 1 injector at a time and take note of how much difference it makes, if 1 or 2 cylinders make little to no difference in idle quality (eg how rough it is) then you have somewhere else to look.
Also a compression test wouldn't go astray.
 

wod300

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Funnily enough I've just ordered a tech 2 and should get it by week's end.

The plugs that were in the car were actually BPR6EFIX-15 and I think they're made for the n/a engine, and I measured the gap on them at 2millimetre!

How long should I leave the new plus in before I pull them out and check them?
 

wod300

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sorry, I also meant to ask if this issue would cause poor fuel economy?
 
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Decicrate

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To start with they are the wrong plugs for the L67. they should end in 13, as in 1.3mm plug gap.
What plugs were put back in?
 

Drewie

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I notice you have a mace memcal fitted, there may be an issue with the tune?
 
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